Abstract

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As the economic burden of treating urinary tract infections (UTIs) is gravely increasing due to multi-drug resistance (MDR) among uro-pathogens, the search for new sources of antimicrobial compounds including bacteriocins has been a priority recently. This study therefore, evaluated the antibacterial activity of bacteriocins against multi-drug resistant bacteria implicated in UTIs. Fermented food (ogi, tapioca, palm wine, kunu, raw milk, and unripe plantain) samples were collected and screened for bacteriocin-producing bacteria using standard microbiological methods. Cell-free bacteriocn was extracted from the screened isolates by centrifugation and tested against MDR Escherichia coli (MDREc) and Staphylococcus aureus (MDRSa) using agar-well diffusion method. Bacteriocin-producing bacterial isolates with high antibacterial activity were identified using PCR and sequencing methods. A total of eight isolates produced bacteriocins with antibacterial activity against E. coli MDREc (7.0 ± 0.40 mm to 19.0 ± 0.99 mm) and S. aureus MDRSa (4.0 ± 0.5 mm to 14.0 ± 0.49 mm). The MIC for the cell-free extracts ranged from 15.63 mg/ml to 31.25 mg/ml against E. coli MDREc and 31.25 mg/ml to 62.50 mg/ml against S. aureus MDRSa, while MBC was at 125 mg/ml to 250 mg/ml and 250 mg/ml against the organisms, respectively. Cell-free extracts of bacteriocin producing isolates obtained from kunu (KU-BPI(B)), raw milk (M-BPI(A)), and unripe plantain (PN-BPI(B)) had significantly (P < 0.05) higher antibacterial activity and the isolates were identified as Morganella morganii KU, Proteus vulgaris CM, and Alcaligenes feacalis PN, respectively. Hence, these isolates produced bacteriocins with broad spectrum bacteriostatic and bactericidal activity against multi-drug resistant E. coli MDREc and S. aureus MDRSa implicated in UTIs.

Keywords: Bacteriocins, Antibacterial activity, Multi-drug resistant bacteria, Urinary tract infections